Direction signal switch operating mechanism



E. L. BARcus 3,363,071

DIRECTION SIGNAL SWITCH OPERATING MECHANISM Jane 9, 1968 Filed June 17, 1965 United States Patent Ofilice 3,363,571 Patented Jan. 9, 1968 3,363,071 DIRECTION SIGNAL SWITCH OPERATING MEIIHANISM Edward L. Barcus, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich., a corporation of Deiaware Filed June 17, 1965, Ser. No. 464,809 4 Claims. (Cl. ZOO-61.34)

ABSTRACT OF TI-IE DISCLOSURE A direction signal switch operatnig mechanism including a pair of snap-in flexible polypropylene cancelling pawls. Each pawl is provided with an inclined cam follower surface for engagement by a cancelling cam during return of the mechanism to a neutral position to reduce the speed at which the mechanism is returned, thus reducing the possibility of over-cancellation of the unit. The characteristics of the pawl material insure a slow rate of return from the deflected pawl position to the normal pawl position, thus eliminating objectionable clicking of the pawls during execution of the turn.

This invention relates to direction signal switch operating mechanism and more particularly to an improved mechanism including a canceling pawl arrangement providing silent operation and insuring effective automatic cancellation.

In semi-automatic direction signal mechanisms, the switch actuating member of the mechanism is manually placed in an operating position by the vehicle driver and is automatically returned to the neutral or inactive position upon completion of a turn. In general the switch actuating member is provided with canceling pawls and the vehicle steering wheel or steering shaft is provided with canceling cams adapted when the mechanism is in an operative position to engage one of the pawls during both the execution of a turn and upon return of the vehicle to a straight ahead direction after completion of the turn. The engaged canceling pawl is moved to a deflected position by the cams in the first instance without effecting the position of the switch actuating member but in the latter instance, the force of the cams is transmitted through the pawls to the actuating member returning the actuating member to the neutral position. In the first instance, the return of the pawl from its deflected position to its original position may produce a clicking noise resulting from engagement of the pawl with the actuating member. In the second instance, the force applied to the pawl under certain circumstances is sometimes so great that the inertia of the switch actuating member and operating lever is sufficient to carry the actuating member through the neutral or inactive position and into the opposite turn indicating position. This latter occurrence is often referred to as overcancellation.

In accordance with the present invention, the overcancellation problem existing in certain prior art mechanisms has been obviated by the utilization of a separate pawl adapted to be snapped into a socket formed in the switch actuating member. With this arrangement the pawl pivot axis can be located such that the cam follower surface of the pawl presents a gradual inclination in the desired direction for cancellation which greatly reduces the speed as the actuating member is returned to the neutral position. The snap-in pawl of the present invention is formed of a material which evidences a time delay when returning to its normal position from a flexed position. Thus, during the execution of a turn when the pawl is deflected by the canceling cam, its return to the normal position into engagement with the switch actuating member is relatively slow and the objectionable clicking noise found in certain prior art mechanisms is eliminated.

A more complete understanding of the present invention may be had from the following detailed description which should be read in conjunction with the drawings in which:

FIGURE 1 is a plan view of a direction signaling mech anism constructed in accordance with the present invention;

FIGURE 2 is a similar to FIGURE 1 and shows the mechanism in a right turn indicating position;

FIGURE 3 is an exploded view showing the canceling pawl disassembled from the switch actuating member;

FIGURE 4 is a sectional view taken along lines 44 of FIGURE 1.

Referring now to the drawings and initially to FIG- URE 1, the direction signal switch operating mechanism of the present invention comprises a support member 10 enclosed within and secured to a steering column 12. An arcuate shaped switch actuating member 14 is provided with a projecting shaft 15 which is rotatably received by the support member 10 and secured thereto. The member 14 terminates in integrally formed socket 16 and 18 adapted to receive a pair of canceling pawls 20 and 22, respectively. In the neutral position as shown in FIG- URE 1, the pawls project inwardly toward the path of travel of a pair of canceling cams 24 which are secured to the vehicle steering wheel (not shown) and are moved thereby in an orbital path about the vehicle steering shaft 26. Each of the pawls 20 and 22 when in their normal undeflected position as shown in FIGURE 1 abut an integrally formed projection 28 extending from the member 14. The switch actuating member 14 is releasably maintained in the neutral position by projecting fingers 30 extending from the support member 10 which engage detent portions 32 which form a part of the member 14. The member 14 may be manually moved to a left or right turn indicating position by an operating lever 34 to position the appropriate pawl in the path of movement of the cams 24.

Referring now to FIGURE 3, the pawl 20 which is identical with the pawl 22 is adapted to be snapped into the socket 16 and releasably maintained therein by projections 36 which extend from an upper portion 38 as shown in FIGURE 4. The intermediate body portion 40 is pro vided with a reduced section 42 which serves as a hinge for the pawl 20. The pawl 20 is preferably formed of polypropylene which has remarkable fatigue resisting properties. Under normal operation the pawl 20 will bend indefinitely at the hinge section 42 and return at a slow rate of speed.

Referring now to FIGURE 2 the direction signal switch mechanism is shown in the right turn indicating position. In this position the pawl 20 is rocked about the pivot axis of the member 1-4 into the path of travel of the cams 24. During the execution of the turn, cams 24 revolve in a clockwise direction and engage the side 44 of the pawl 20. The pawl 29 is flexed about the hinge section 42 to the dotted line position each time the pawl is engaged by one of the cams 24. After disengagement by the cam 24, the pawl returns to its normal position in abutment with the projection 28. The return to this position is, however, at a slow rate of speed and thus the objectionable clicking noise which is evidenced in the prior art mechanisms when the pawl engages the stop member 28 is eliminated with the present mechanism. After the turn is completed, the cams 24 begin to revolve in a counterclockwise direction. Since the pawl 20 is in engagement with the stop 28, the force exerted by the canceling cam 24 on the pawl 28 is transmitted to the member 14 thus returning it to the neutral position as shown in FIGURE 1. It will be noted, however, that the cam follower surface 46 is gradually inclined rather than forming an abrupt surface engagement which allows the return of the actuating member 14 to the neutral position through a greater steering wheel movement. Normally, the actuating member 14 is moved approximately 7 about its pivot axis during return from the switch actuating position to the neutral position from an operating position. In the prior art mechanisms, this is accomplished by 2 to 3 movement of the steering wheel. In the present in- "vention the gradual change in the cam follower surface 46 permits the 7 movement of the member 14 during a steering wheel movement of approximately 15 to 18. Since the same amount of work is done with six times as many degrees of travel of the cams 24, the speed at which the member 14 is returned to the neutral position is approximately ,4; as fast as with prior art mechanisms. With this greatly reduced speed, the inertia of the actuating member 14 and the lever 34 is not great enough to overcome the holding effect of the detent mechanism formed by the fingers 30 and detent portion 32 thus preventing the member 14 from being driven into a left turn indicating position from a right turn indicating position.

While the operation of the mechanism has been described with regard to a right turn indicating position, it will be apparent that the mechanism will operate in a similar manner when the parts are positioned to indicate a left turn.

While the invention has been described with regard to a preferred embodiment thereof, this should not be construed in a limiting sense. Modifications and variations will now occur to those skilled in the art. For a definition of the invention, reference is made to the appended claims.

I claim:

1. A direction signal switch operating mechanism for use with cam means movable in an orbital path, said cam means being movable in a first direction during execution of a turn and in an opposite direction after execution of the turn,

said mechanism comprising a support member,

an actuating member pivotally mounted to said support member for movement about a pivot axis, 7

said actuating member including an integrally formed socket on opposite sides of said pivot axis,

a pair of flexible pawls each having'one end mounted in one of said sockets and a projecting body portion extending toward the path of travel of said cam means, one of said pawls being movable into the path of travel of said cam means when said actuating member is in a switch operating position,

said actuating member including a projection adjacent one side of each of said body portions when said pawls are in a normal position,

said body portions including a reduced section forming a hinge between the opposite end portions of each of said pawls,

said one of said pawl being engageable by and thereafter movable with said cam means from said normal position to a deflected position out of the path of travel of said cam means during movement of said cam means in said first direction,

said pawls being formed of a material exhibiting a slow rate of return to said normal position from said deflected position to prevent snap action engagement with said projections,

the opposite end of said pawls presenting an inclined cam follower surface to said cam means upon movement thereof in said opposite direction to control the speed of return of said actuating plate to said neutral position.

2. A direction signal switch operating mechanism for use with cam means movable in an orbital path, said cam means being movable in a first direction during execution of a turn and in an opposite direction after execution of the turn,

said mechanism comprising support means,

an actuator plate supported by said support means and movable from a neutral position to a switch operating position,

said actuator plate including an arcuate body portion terminating at opposite ends in a socket,

a pair of pawls each having an end portion mounted in a socket and each having a body portion normally abutting on one side thereof an extension of said actuator plate,

the opposite end portion of one of said pawls extending into the path of travel of said cam means when said actuator plate is in a switch operating position,

the body portion of said pawls having a hinge section between the ends thereof, said one of said pawls being engageable by and thereafter movable with cam means from a normal position to a deflected position out of the path of travel of said cam means during rotation of said cam means in said first direction,

said pawls being formed of a material exhibiting a slow rate of return to said normal position from said deflected position to prevent snap action engagement with said extension,

said opposite end portion presenting an inclined cam follower surface to said cam means upon rotation thereof in an opposite direction to control the speed of return of said actuator plate to said neutral position.

3. A direction signal switch operating mechanism for use with cam means movable in a circular path, said cam means being movable in a first direction during execution of a turn and in an opposite direction after execution of the turn,

said mechanism comprising a support member,

a switch actuating member,

means pivotally mounting said actuating member to said support member for movement about a pivot axis,

detent means for releasably maintaining said actuating member in either a neutral or switch operating position,

said actuating member including integrally formed socket means on each side of said pivot axis,

a polypropylene pawl mounted in each of said sockets and normally abutting on one side an integral projection of said actuating member,

an operating lever for moving said actuating member from a neutral position wherein said pawls are out of die path of travel of said cam means to an operating position wherein one of said pawls is moved into the path of travel of said cam means,

each of said pawls including a body portion having a reduced hinge section and terminating in an inclined cam follower surface,

movement of said cam means in said first direction engaging said one side of one of said pawls when said actuating member is in said operating position to move said pawl to a deflected position out of the path of travel of said cam means without affecting the position of said actuating member,

said pawls exhibiting a slow rate of return to the normal position from the deflected position to prevent snap action engagement with said projection,

movement of said cam means in an opposite direction engaging the inclined cam follower surface of said pawl to return said actuating member to the neutral position.

4. A direction signal switch operating mechanism for use with cam means moveable in an orbitable path, said cam means being moveable in a first direction during execution of a turn and in an opposite direction after' execution of the turn, said mechanism comprising support means, a switch actuating member, means pivotly mounting said actuating member to said support means for movement about a pivot axis, said actuating member including a socket on each side of said pivot axis, a flexible pawl mounted in each of said socket and extending toward the path of movement of said cam means, an operating lever for moving said actuating member from a neutral position wherein said pawls are out of the path of travel of said cam means to an operating position where one of said pawls is moved into the path of travel of said cam means, each of said pawls including means at one end receivable in said sockets and an inclined cam follower surface at the opposite end, said pawls further including a reduced section between said ends operating as a hinge to allow flexing of the pawls from a normal position to a deflected position during movement of said cam means in said first direction while said actuating member is in an operating position, stop means formed on said actuating member normally engaging said pawl: when said pawls are in said normal position, said pawl: being formed of a material exhibiting a slow rate 0 return to said normal position from said deflected posi tion to prevent snap action engagement with said stor means, said inclined cam follower surface being engag able by said cam means during movement in said oppositt direction to return said actuating member to said neutra position from said operating position.

References Cited UNITED STATES PATENTS 3,207,867 9/1965 Marquis et a1 200-61.3 3,254,169 5/1966 Fuqua ZOO- 61.3

BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner. 

